Review on Wearable Antennas: Part 2: Recent advances and applications.

Wearable antennas assume a critical role in wearable devices and systems, facilitating real-time remote data and energy transmission wirelessly. Unlike their conventional rigid counterparts, wearable antennas impose more stringent criteria. In addition to necessitating flexibility and conformity to the human body, wearable antennas demand compactness to fit in miniature wearable devices while maintaining satisfied radiation performance. Furthermore, these antennas are expected to possess multi-band or wideband operational capabilities to suit diverse application scenarios and Industrial, Scientific, and Medical (ISM) bands. Additionally, preference is given to antennas that are reconfigurable, permitting tunability of frequency, radiation pattern, and polarization. Such adaptability renders the antenna suitable for both on-body and free-space operations, or scenarios necessitating modifications to the functionality of wearable devices without necessitating alterations to other components. In pursuit of these objectives, diverse wearable antenna prototypes have recently been developed. This comprehensive review systematically presents recent advancements in miniature, multi-band and wideband, and reconfigurable wearable antennas, examining their applications in health monitoring, tracking, and energy harvesting, providing valuable insights for the development of wearable antennas and systems.